Gas generation system



June 30, 1964 F. L. OPPENHEIMER ETAL GAS GENERATION SYSTEM Filed Oct. 20, 1960 REGULA 7'08 VAL VE PIEESSUE/Z/NG MEU 3 SheetsSheet l A TTORNE) S June 30, 1964 F. L. OPPENHEIMER ETAL 3,138,928

GAS GENERATION SYSTEM Filed Oct. 20, 1960 5 Sheets-Sheet 2 TORQUE MOTOR S E RVO MOTOR MAGNETIC AM PLIF IER FREQUENCY DISCRIMINATOR FREQUENCY EEFEEENCE IN V EN TOR. Frank L. Oppenheimer .Sc/nusdf er Pay BY Babe/l .5. Mai as ATTORNE SIGNAL SOURCE June 30, 1964 F. 1.. OPPENHEIMER ETAL 3,138,928

GAS GENERATION SYSTEM Filed Oct. 20. 1960 3 Sheets-Sheet 3 ATTORNEY United States Patent 3,138,928 GAS GENERATION SYSTEM 7 Frank L. Oppenheimer, University Heights, Roy C.

Schweitzer, Highland Heights, and Robert S. Mathias, Kirtland, Ohio, assignors to Thompson Ramo Wooldridge Inc, Cleveland, Ohio, a corporation of Ohio Filed Oct. 20, 15 66), Ser. No. 63,793 6 Claims. (Cl. 6ll--39.48)

This invention relates to gas generation systems and more particularly to improved methods and means for generating gases and controlling the flow of the gas producing fuel to the gas generator.

Heretofore, typical gas generation means employed with missiles, rockets and the like have been self-contained. Such gas generation means normally comprised a gearbox-driven fuel pump which provided fuel to the gas generator after the gas generation system had been started. Use of fuel pumps has the inherent disadvantage in such self-contained gas generation systems of bootstrap starting. System operation had to reach a certain level before the pump could independently provide fuel at the required pressure and flow rate to maintain. the system operable. Thus, quick starting of the systems was virtually impossible unless an outside, independent and ground-supplied power source was used to initially drive the fuel pump.

In additiomto the above disadvantage, present-day monofuels require purging of the gas generator to clear the system of fuel which is ignitible at the high heat levels remaining after system shut-down. Consequently, re-

start of the system was prevented because, in the purging operation, the pressurizing medium supply for the fuel tank was exhausted.

With the present invention, we substantially eliminate the problems and diificulties of the prior art and provide self-contained gas generation systems which are operable for extended durations, levelly re-startable, quick starting and self-contained.

It is therefore an object of the present invention to provide improved auxiliary power supply systems for rockets, missiles and related air and space-borne vehicles.

It is another object of the present invention to provide self-purging and quick starting auxiliarypower supply systems for rockets, missiles and related air and spaceborne vehicles.

' It is still another object of the present invention to provide re-startable and self-contained gas generation systems having improved fuel control means.

It is another object of the present invention to provide improved auxiliary power supply systems operatively responsive to the output of the system for control of the fuel supply. I

It is a further object of the present invention to provide improved modulating 'valve means adapted to control fuel flow to the gas generator of auxiliary power supply systems without the requirement for a fuel pump.'

It is another object of the present invention to provide improved methods for generating gases for operation pf auxiliary components of missiles, rockets and related air andspace-borne vehicles which are self-controllable.

Another object of the present invention is to provide improved gas generation apparatus'which is simple and compact in construction and high speed and efficient in operation. v g

These and other objects, features and advantages of the present invention will become more apparent froma careful consideration of the following detailed descrip-.

tion when considered in conjunction with the accompanying drawings illustrating a preferred embodimentof the present invention and wherein like reference numerals and characters refer to like and corresponding parts throughout the several views.

- On the drawings:

FIGURE 1 is a generally schematic view of a preferred embodiment of the gas generation system of the present invention.

FIGURE 2 is a block diagrammatic view of the control means for the fuel flow modulating valve.

FIGURE 3 is a view in partial section of the preferred embodiment of the modulating valve of the present invention.

FIGURE 4 is a fragmentary view in partial elevation of the cam means controlling operation of the modulating valve.

FIGURE 5 is a view taken along lines VV of FIG- URE 3.

FIGURE 6 is a schematic view illustrating the operation of the modulating valve of FIGURE 3.

FIGURE 7 is 'a view taken along lines VIIVII of FIGURE 3.

As shown on the drawings:

As appears in FIGURE 1, a preferred embodiment of a gas generation system of the present invention may include a plurality of containers 7 to provide a source of an inert pressurizing medium, such as nitrogen, connected by a conduit 8 and a pressure regulator 8a of conventional construction to a monofuel' containing tank 9 for pressurization thereof to feed the monofuel through a conduit 16) to the reaction chamber of a gas generator 11. Connected in conduit 10 is a normally closed fuel shut-oif valve 12 energizable from a remote source, such as the autopilot system (not shown) of'the air or space and construction of the modulating valve being described in detail hereinafter.

The chamber of the gas generator 11 is connected through a gas discharge outlet 14 to the turbine chamber of a turbine housing 15 for driving of the turbine 16. The turbine 16 is connected through its shaft to reduction gearing 17 and reduction gearing 17 may be connected to one or more drive shafts 18and 19 of auxiliary components 18a and 19a respectively, such as air conditioning units or fan pumps, of the vehicle with which the gas generation system isemployed and to the shaft Zila of a conventional axial impeller type gas pump 20 for operation thereof. j

Thus a conventional monofuel may be fed under pressure through the modulating valve and initially' ignited hypergolically with a suitable oxidizer, such as nitric acid,"

introduced into the gas generator by conventional means (not shown) and the gaseous products of reaction ex- I, hausted through the discharge nozzle 14 into the turbine chamber to drive turbine 16 and the gearing 17, shafts 18,

19 and 20a and the components coupled thereto. The' major portion ofthe exhaustgases exit through an outlet 21 to the atmosphere and the remainder of the exhaust gases by-pass through a conduit'22 connecting the tur-' bine housing to a conduit23. Connected in conduit 23 is a conventional heat exchanger 24 for cooling of the exhaust gases and a gasfilter .25. Conduit 23-connects the turbine housing through the'heat exchanger 24 and,

filter 25 to the gas pump 20. Thus, the cooled and filtered exhaust gases are flowed from the gas pump 20 under a pressure substantially equal tov the required pressure in the fuel tank pressurizing bottles 7 and at a ratecontrolled by the gas pump. Operation of the gas pump cooled and filtered exhaust gases flow into a conduit 26 under the influence of the gas pump. Conduit 26 is connected through a one-way check valve 27 to the fuel tank pressurizing medium outlet 7a and from the outlet 7a the exhaust gases flow into line 8 for pressurization of the fuel tank 9.

Thus a boot-strap replenishment system is provided for the fuel tank pressurization system and the requirement for an auxiliary fuel pump and gas purge system are eliminated. The elimination of these components constitute features of the present invention.

As appears in FIGURES 3-5 and 7 the modulating valve assembly, generally indicated by the numeral 13 may include a housing 30 chambered as at 31 in communication with the inlet side a and outlet side 1611 of conduit 10. The housing is provided with a removable boss 32 used for instrumentation and inspection and is secured to housing 30 as by screws 33, and a seal 34 may be employed to effectively prevent leakage of fuel from the chamber 31. Boss 32 is passaged as at 35, and the passage 35 is adapted for connection to an appropriate fitting.

Housing 30 is passaged also as at 38 in communication with the chamber 31 to receive a threaded sleeve fitting 39. The passage 38 is counterbored to provide a shoulder 41 as a seat for the sleeve 39. Sleeve 39 may be grooved to receive seals 42 and 43. A passage 44 is formed in the sleeve 39 to communicate the sleeve and chamber 31.

At a position directly opposite the sleeve 39 is passage 45 in housing 31 adapted for connecting chamber 31 to an appropriate fitting (not shown) at the outlet side 10!) of conduit 10 to permit communication between the chamber 31 and conduit 10 (FIGURE 1).

The housing chamber wall 46 is passaged to receive a sleeve 47 having an outwardly flaring annular flange 47a which cooperates with a shoulder 46a of the chamber wall counterbore 46b to seat a seal 48. The housing wall 46 is grooved to receive a seal ring 49 and, for securing sleeve 47. Associated with the modulating valve is a conventional 115 VAC servo motor 51 operatively responsive to a signal received from the control system 100, shown in FIGURE 1, to vary the rate of flow of monofuel to the gas generator 11.

Shaft 52 passes through a guide 53 in sleeve 47 and extends into chamber 31 to form an offset crank cam 54 (FIGURES 3 and 4) for purposes hereinafter more fully described. A bearing 55 is employed for shaft 52 and is secured against a shoulder 56 of the sleeve 47 by pressure of the monofuel in chamber 31.

Shaft 52 extends a distance into chamber 31 and forms an offset crank to give desired cam action, as clearly ap pears in FIGURES 5 and 4.

The offset 54a of the cam, 54-, is rectangular in crosssection and is integral with and perpendicular to the generally cylindrical leg 59 of the cam. The leg 59 is sized to a bearing 60 (FIGURES 3 and 5) and is provided with an annular groove 61 to receive a complementary retaining'ring 62 which cooperates with a circular flange washer 63 carried by the cam means 54 to maintain the bearing in the desired position (FIGURES 3 and 4),

A metering pin cam guide track 64 is provided with slot 64a across the entire width of the guide to receive the bearing 60 and cam leg 59. The retaining ring 62 and retaining flange 63 maintain the bearing 60 and cam leg 59 in the slot 64a. i

As appears in FIGURES 3 and 5 the cam guide 64 is 1 metering piston 66 is provided With three fiat surfaces66a,

66b and 660. 3 Each surface 66a, 66b and 660 terminates inwardly of the sides 67, 68 and 69, of the piston and each of said surfaces iisinwardly tapered, the taper terminating at points apart on the diameter of piston 66 to form a three sided guide for piston 66 to slide in sleeve 39. The surfaces 67, 68 and 69 form frusto-conical segments in piston 66 (FIGURE 7).

Formed in the piston 66 on three sides at 120 spacing are three circular chord passages 70, 71 and 72 defining with the inner wall of the sleeve passage 4-4 three fuel flow paths. Passages 70, 71 and 72 are each tapered outwardly a short distance from the end of the piston adjacent the cam guide and are of equal area over their major length adjacent the conduit inlet 16a (FIGURE 3). Thus communication is permitted through the flow passages 70, 71 and '72 between the conduit 10 and chamber 31. The total area of the flow path defined by the passages 70, 71 and 72. may be varied, because of the taper of the passages, by moving the piston 66 in the sleeve 39.

Movement of the piston 66 is accomplished by rotation of the shaft 52 which in turn moves the cam means 54 and cam guide 64 connected to piston 66 to the right as viewed in FIGURE 5. Movement of the cam guide 64 causes movement of the piston 66 and because of the taper thereof increases the total cross-sectional flow path in the sleeve 39 thereby varying the flow rate in and out of chamber 31. It will be appreciated of course that the piston is initially positioned in the sleeve 39 so that the total flow area in the sleeve is at a minimum. The contour of the passages 71), 71 and 72 are so shaped that the fuel flow paths defined by the sleeve 39 and piston passages 7t), 71 and 72 are of variable total area at any cross-section across the tapered sides 67, 68 and 69.

Additionally, shaft 52 and piston 66 cooperate to maintain the cam guide 64- in spaced relation to the walls of the chamber 31.

Linear angular motion of shaft 52 will produce nonlinear movement of the piston 66 in the sleeve passage 39 and therefore, will vary non-linearly, the area of the open fuel flow path defined by the sleeve passage walls and the piston. Linear control of the rate of flow of the fuel to the gas generator from the chamber 31 via conduit 10 is performed by non-linear area variation through the piston 66 coupled with a linear pressure drop between points 10a and 16b of conduit 10.

The modulating valve 13 is capable of metering fuel flow to the gas generator 11 without requiring a fixed pressure drop across the metering sleeve thereby permitting utilization of a pressurized fuel system and the elimination of the requirement for a fuel pump.

The fuel flow, from the laws of fluid dynamics, is a function of several variables in accordance with the following formula:

W =CA /2gpAP where:

W =fuel flow rate, lb./sec.

C=coefficient of discharge, constant A =area of valve opening, in.

g=gravitational force, in./sec. -constant =density, lb./in. -constant AP=pressure drop across valve opening, lb./in.

In many applications, the pressure drop across a valve opening is held constant; therefore, fuel flow varies directly with the area of the valve opening. However, in the present application, the pressure drop across the valve opening defined by the sleeveand passages of the piston 66 cannot be held constant because the present pressurized system does not require a low pressure sump normally flow since the valve upstream pressure is maintained constant by the pressure regulator 8a. It will be appreciated that the pressure regulator is calibrated to provide a minimum flow rate to the gas generator 11 at least equal to the burning rate of the monofuel in the chamber to prevent burnback in conduit 10. The shape and total flow area defined by the piston 66 and sleeve 39 to maintain the fuel flow rate according to the required pressure dropflow area relationship will vary depending upon these requirements. Such requirements are well within the skill of the art.

' The modulating valve 13 is controlled by a control system which may include a tachometer generator 101 coupled to the turbine 16 through gearing 17 so that the frequency of the generator 101 is identical or proportional to the frequency or the output of the gas generator 11.

The output of the tachometer 101 is coupled through the modulating valve control system 100 which includes a frequency discriminator system 103 which feeds an output that has a sign and amplitude which are a function of the variation in frequency between the output of the tachometer 101 and a pre-selected standard control or reference frequency. As appears in FIGURE 2, the frequency discriminator 103 feeds an error signal to a magnetic amplifier 105 or the like as a preferred form of control device which, in turn, provides its output to the torque motor 51 coupled to the modulating valve. The error signal is converted in the torque motor shaft to a mechanical error signal which operates the torque motor shaft 52 and rotates the shaft in the desired direction to thereby control the flow pressure in the chamber 31 by movement of the cam and cam housing 64 and associated piston 66. Thus effective means are provided for controlling the rate of flow of fuel to the gas generator 11. A feed back network 106 is coupled to measure modulating valve fuel flow rate upstream of the gas generator 11. The feed back network feeds itsoutput voltage which is proportional to the" modulating valve velocities-to the magnetic amplifier 105 for control of the amplifier system 105. An appropriate valve control system readily adaptable to the present invention is disclosed in US. Patent No.'2,-790,091 issued'on the application of Chatman et al.

In operation, the tachometer generator 101 supplies the signal to the frequency discriminator 103 which has an output potential proportional in sign and amplitude to the deviation of the speed of the turbine from the no load speed setting or pre-established proper operating frequency of the system. If the speed is low due to the application of a load by the accessory components 18 and 19, the magnetic amplifier 105 feeds a signal to the torque motor shaft which in turn rotates, and in rotating, moves the' cam 54 and cam housing 64 to the right in FIGURE 5 thereby increasing the cross-sectional area; of the fuel flow path defined by the piston 66 and sleeve 39 to increase the rate of fuel flow to the gas generator 11. The continued existence of the error signal operates to maintain this desired fuel flowrate by maintaining the piston in the required position relative to the sleeve 39. 1 If on the other hand: the modulating valve control system 100 senses an increase in turbine speed over the pre-selected value an error output is produced to return, the torque shaft to the desired position. thereby moving the cam housing 64-and piston 66 to the left until the desired pre-selected turbine speed is obtainedwhereupon" the cam housing 64, piston 66 and cam 54 are in the position shown in section in FIGURE 5. The feed bac signal derived through the feed back network 106 is employed to control operation of the magnetic amplifier in accordance with well known principles.

In operation, an electrical start signal from aground start console (not shown) activates the pressure regulator 8a to admit the required amount of'pressurizing medium from the gas containers 7 to the fuel tank 9 through line 8. Simultaneously, the electrical start sigaisa as 6 nal may open the fuel shut-off valve 12 and the monopropellant fuel is fed from the fuel shut-off valve to the fuel modulating valve, which is in thefull open position, the rate of flow of the fuel to the gas generator being controlledby the modulating valve 13. The initial position of the modulating valve piston 66 is in the full open position shown in FIGURE 5. The fuel is initially ignited hypergolically by contact with an acid oxidizer such as fuming nitric acid admitted through conventional means (not shown) to the gas generator 11. Control of the proportion of the'acid fed to the gas generator is from the ground console (not shown). Once reaction conditions are established in the gas generator, the supply of the acid to the gas generator is terminated and the monofuel reacts to produce the gaseous products of reaction. The gases then flow through the outlet 14 for driving turbine 16 and a portion of the gases are exhausted through the conduit 21. The remainder of the exhaust gases flow through the outlet 22 through line 23 where it is cooled in the heat exchanger 24 and filtered in the filter 25. The gas then flows through the gas pump 20 operated by the gearing 17 and flows through the conduit 26 and check valve 27 for maintaining the pressure level in the containers 7 and providing means for continuing feed of the mono-propellant from the fuel tank 19 through the line conduit 10 to the gas generator 11. The tachometer 101 and control system control, through the torque motor 51, the operation of the modulating valve 13 to assure that the pre-selected fuel feed rate to the gas generator 11 is maintained in accordance with the practice outlined above.

The gas generation system of the present invention is self-contained, is provided with a fuel flow rate control system operable over a range of fuel flow rate and includes a self-operable system for replenishing the fuel tank pressurization medium. The requirements for a fuel pump and an auxiliary purge system are eliminated.

Although various minor modifications might be suggested by those versed in the art, it is to be understood that we wish to embody Within the patent warranted hereon all such embodiments as reasonably and properly come within the scope of our contribution to the art.

We claim as our invention:

1. A gas generation system comprising:

a source of fuel,

gas generation means,

a source of a pressurized medium,

first conduit means connecting the source of pressurized medium and the source of fuel to pressurize said fuel,

a pressure regulating valve connected to said first conduit means to regulate the flow of the pressure medium to the fuel source to supply the fuel source with a constant predetermined pressurization level,

a second conduit means connecting said source of fuel with said gas generation means to deliver fuel to said gas generation means,

means connected to the gas generation means to deliver a portion of the discharge gas from the gas generation means to the source of pressurized medium to maintain the supply of pressurized medium,

a modulating valve assembly connected to the second conduit means, I said modulating valve assembly having a flow chamber formedtherein and said flow chamber having an inlet connected to the source of fuel, an outlet connected to the gas generation means, a metering piston havinglthree flat inwardly tapered surfaces slidably mounted in the inlet to form a plurality of flow passages therewith leading into the flow chamber, said piston having a portion thereof normally extending into said flow chamber and being I shaped so that the sliding thereof in theinlet '2 varies the cross-sectional fuel flow area of the piston flow passages,

a servo motor connected to the piston to slide said piston in the inlet to vary the cross-sectional fuel flow area of the piston flow passages, and a control system connected to the gas generation means and to the servo motor whereby said fuel flow area is varied to maintain a preselected fuel feed rate to the gas generator in accordance to the desired gas generator output.

2. A gas generation system adapted for use in airborne, space-borne vehicles and the like comprising:

a source of fuel,

gas generation means,

a source of a pressurized medium,

first conduit means connecting the source of pressurized medium and the source of fuel to pressurize said fuel a pressure regulating valve connected to said first conduit means to regulate the flow of the pressure medium to the fuel source to supply the fuel source with a constant predetermined pressurization level,

a second conduit means connecting said source of fuel with said gas generation means to deliver fuel to said gas generation means,

means connected to the gas generation means to de liver a portion of the discharge gas from the gas eneration means to the source of pressurized me-' dium to maintain the supply of pressurized medium, a modulating valve assembly connected to the second conduit means, said modulating valve assembly having a flow chamber formed therein and said fiow chamber having an inlet connected to the source of fuel,

an outlet connected to the gas generation means,

a metering piston having three fiat inwardly tapered surfaces slidably mounted in the inlet to form a plurality of flow passages therewith leading into the flow chamber,

said piston having a portion thereof normally extending into said flow chamber and being shaped so that the sliding thereof in the inlet varies the cross-sectional fuel flow area of the piston flow passages,

21 metering cam guide track slidably mounted in said flow chamber and having an end thereof connected to an end of said piston to slidably move said piston when said track moves,

an offset cam connected to said guide track,

a shaft extending into the flow chamber and having one end connected to said offset cam Where in oscillation of the shaft causes the guide track to slide,

a servo motor connected to theother end of the shaft to oscillate said shaft, and a control system connected to the gas generation means and to the servo motor whereby said fuel flow area is varied to maintain a preselected fuel feed rate to the gas generator in accordance to the desired gas generator output.

3. A gas generation system adapted for use in airborne, space-borne vehicles and the like comprising:

a source of fuel, gas generation means, a source of a pressurized medium, first conduit means connecting the source of pressurized medium and the source of fuel to pressurize third means connected to the gas generation means to deliver a portion of the discharge gas from the gas generation means to the source of pressurized medium to maintain the supply of pressurized medium, said third means comprising means to cool the portion of the discharge gases being delivered to the source of pressurized medium, and

check valve means to control the amount of discharge gases delivered to said source of pressurized medium,

a modulating valve assembly connected to the second conduit means, said modulating valve assembly having a flow chamber formed therein and said flow chamber having an inlet connected to the source of fuel,

an outlet connected to the gas generation means,

a metering piston having three flat inwardly tapered surfaces slidably mounted in the inlet to form a plurality of flow passages therewith leading into the flow chamber,

said piston having a portion thereof normally extending into said flow chamber and being shaped so that the sliding thereof in the inlet varies the cross-sectional fuel flow area of the piston flow passages,

a metering cam guide track slidably mounted in said flow chamber and having an end thereof connected to an end of said piston to slidably move said piston when said track moves,

a shaft extending into the flow chamber and having one end connected to said offset cam wherein oscillation of the shaft causes the guide track to slide,

a servo motor connected to the other end of the shaft to oscillate said shaft, a control system connected to the gas generation means and to the servo motor whereby said fuel flow area is varied to maintain a preselected fuel feed rate to the gas generator in accordance to the desired gas generator output.

4. A gas generation system adapted for use in airborne, space-borne vehicles and the like comprising:

a source of fuel, gas generation means, a source of a pressurized medium, first conduit means connecting the source of pressurized medium and the source of fuel to pressurize said fuel a pressure regulating valve connected to said first conduit means to regulate the flow of the pressure medium to the fuel source to supply the fuel source with a constant predetermined pressurization level, a second conduit means connecting said source of fuel with said gas generation means to deliver fuel to said gas generation means, third means connected to the gas generation means to deliver a portion of the discharge gas from the gas generation means to the source of pressurized medium to maintain the supply of pressurized medium, said third means having cooling means to cool the portion of discharge gases being delivered to the source of pressurized medium, and

check valve means to control the amount of discharge gases delivered to said source of pressurized medium,

a modulating valve assembly connected-to the second conduit means, said modulatingvalve assembly having a flow chamber formed therein and said flow chamber having an inlet connected to the source of fuel, an outlet connected to the gas generation means, a metering piston having three flat inwardly tapered surfaces slidably mounted in the inlet to form a plurality of flow passages therewith leading into the flow chamber,

said piston having a portion thereof normally extending into said flow chamber and being a servo motor connected to the piston to slide said piston in the inlet to vary the cross-sectional fuel flow area of the piston flow passages, and a control system connected to the gas generation means and to the servo motor shaped so that the sliding thereof in the inlet varies the cross-sectional fuel flow area of the piston flow passages,

whereby said fuel flow area is varied to maintain a preselected fuel feed rate to the gas generator in accordance to the desired gas generator output.

a metering pin cam guide track slidably mounted in said flow chamber and having an end thereof integrally connected to an end of said piston to slidably move said piston When said track moves,

a slot provided across the width of the guide track,

a second conduit means connecting said source of fuel 6. A gas generation system comprising:

a source of fuel,

gas generation means,

a source of a pressurized medium,

first conduit means connecting the source of pressurized medium and the source of fuel to pressurize an offset cam means connected to the shaft having said fuel,

a cylindrical leg and an offset rectangular a pressure regulating valve connected to said first concross-sectional leg, duit means to regulate the fiow of the pressure mebearing means surrounding said cylindrical leg, dium to the fuel source to supply the fuel source said cylindrical leg and said bearing means conwith a constant predetermined pressurization level,

nected to said guide track slot and means maina second conduit means connecting said source of fuel taining said bearing means and cylindrical leg with said gas generation means to deliver fuel to therein, said gas generation means,

a shaft extending into the flow chamber and havmeans connected to the gas generation means to deing one end connected to said rectangular leg liver a portion of the discharge gas from the gas wherein oscillation of the shaft causes the guide generation means to the source of pressurized metrack to slide, dium to maintain the supply of pressurized medium,

a servo motor connected to the other end of the shaft a modulating valve assembly connected to the second to oscillate said shaft, conduit means, a control system connected to the gas generation means said modulating valve assembly having a flow chamber d t th rvo m t formed therein and said flow chamber having whereby said fuel flow area is varied to maintain a prean inlet connected to the source of fuel, selected fuel feed rate to the gas generator in accordan outlet connected to the gas generation means, ance to the desired gas generator output. a metering piston having a plurality of tapered 5. A gas generation system comprising: surfaces slidably mounted in the inlet to form a source of fuel, a plurality of flow passages therewith leading gas generation means, into the flow chamber, a source of a pressurized medium, said piston having a portion thereof normally extendfirst conduit means connecting the source of pressuring into said flow chamber and being shaped so ized medium and the source of fuel to pressurize that the sliding thereof in the inlet varies the crosssaid fuel, sectional fuel flow area of the piston flow passages, a pressure regulating valve connected to said first cona servo motor connected to the piston to slide said duit means to regulate the flow of the pressure mepiston in the inlet to vary the cross-sectional fuel dium to the fuel source to supply the fuel source flow area of the piston flow passages, and with a constant predetermined pressurization level, a control system connected to the gas generation means and to the servo motor with said gas generation means to deliver fuel to said gas generation means, a modulating valve assembly connected to the second whereby said fuel flow area is varied to maintain a preselected fuel feed rate to the gas generator in accordance to the desired gas generator output.

conduit means, said modulating valve assembly having a flow chamber formed therein and said flow chamber having an inlet connected to the source of fuel,

an outlet connected to the gas generation means, iggggg n 3 1 3 igg a metering piston a g a plurality of flat 5 Lane g 00 27 1936 wardly tapered surfaces slida y mounted in the 2555457 S d; Au 21 1951 inlet to form a plurality of flow Passages there 2 31 42 jgwett n 17 1953 with leading into the fl W Chamber, g; Jul 20 1954 said piston having a portion e of normally eXtend' 5 7 Clark N 4 1958 ing into said flow chamb r a being Shaped 2,926,492 Hang; Mgr 1 1960 that the sliding thereof in the inlet varies tne cross- 3,040,522 Williamson et aL June 26, 19 2 sectional fuel flow area of the piston flow passages, 

1. A GAS GENERATION SYSTEM COMPRISING: A SOURCE OF FUEL, GAS GENERATION MEANS, A SOURCE OF A PRESSURIZED MEDIUM, FIRST CONDUIT MEANS CONNECTING THE SOURCE OF PRESSURIZED MEDIUM AND THE SOURCE OF FUEL TO PRESSURIZE SAID FUEL, A PRESSURE REGULATING VALVE CONNECTED TO SAID FIRST CONDUIT MEANS TO REGULATE THE FLOW OF THE PRESSURE MEDIUM TO THE FUEL SOURCE TO SUPPLY THE FUEL SOURCE WITH A CONSTANT PREDETERMINED PRESSURIZATION LEVEL, A SECOND CONDUIT MEANS CONNECTING SAID SOURCE OF FUEL WITH SAID GAS GENERATION MEANS TO DELIVER FUEL TO SAID GAS GENERATION MEANS, MEANS CONNECTED TO THE GAS GENERATION MEANS TO DELIVER A PORTION OF THE DISCHARGE GAS FROM THE GAS GENERATION MEANS TO THE SOURCE OF PRESSURIZED MEDIUM TO MAINTAIN THE SUPPLY OF PRESSURIZED MEDIUM, A MODULATING VALVE ASSEMBLY CONNECTED TO THE SECOND CONDUIT MEANS, SAID MODULATING VALVE ASSEMBLY HAVING A FLOW CHAMBER FORMED THEREIN AND SAID FLOW CHAMBER HAVING AN INLET CONNECTED TO THE SOURCE OF FUEL, AN OUTLET CONNECTED TO THE GAS GENERATION MEANS, A METERING PISTON HAVING THREE FLAT INWARDLY TAPERED SURFACES SLIDABLY MOUNTED IN THE INLET TO FORM A PLURALITY OF FLOW PASSAGES THEREWITH LEADING INTO THE FLOW CHAMBER, SAID PISTON HAVING A PORTION THEREOF NORMALLY EXTENDING INTO SAID FLOW CHAMBER AND BEING SHAPED SO THAT THE SLIDING THEREOF IN THE INLET VARIES THE CROSS-SECTIONAL FUEL FLOW AREA OF THE PISTON FLOW PASSAGES, A SERVO MOTOR CONNECTED TO THE PISTON TO SLIDE SAID PISTON IN THE INLET TO VARY THE CROSS-SECTIONAL FUEL FLOW AREA OF THE PISTON FLOW PASSAGES, AND A CONTROL SYSTEM CONNECTED TO THE GAS GENERATION MEANS AND TO THE SERVO MOTOR WHEREBY SAID FUEL FLOW AREA IS VARIED TO MAINTAIN A PRESELECTED FUEL FEED RATE TO THE GAS GENERATOR IN ACCORDANCE TO THE DESIRED GAS GENERATOR OUTPUT. 